ZAB Statement of Comparability wait times. Real experiences from Americans on §18b?

My situation:

I'm an American with a job offer in Berlin, applying for the §18b Skilled Worker Visa. My university has an H+ rating in Anabin but my specific degree isn't individually evaluated, meaning I need a ZAB Statement of Comparability. I've already submitted the application. My employer MIGHT be willing to initiate the fast-track procedure under §81a, which should compress the ZAB review to two months.

What I'm asking:

For anyone who has been through the ZAB process recently (especially other Americans or people applying from the US):

• How long did it actually take, standard or fast-track?
• Did the fast-track make a meaningful real-world difference or just a marginal one?
• Were there any unexpected delays or things that slowed you down?
• Anything you wish you'd done earlier to speed the process up?

I have a target start date and I'm trying to set realistic expectations. Appreciate any real experiences.